---
title: Overview
---

[Document loaders](/oss/concepts/document_loaders) load data into LangChain's expected format for use-cases such as [retrieval-augmented generation (RAG)](/oss/langchain/rag).

LangChain.js categorizes document loaders in two different ways:

- [File loaders](/oss/integrations/document_loaders/file_loaders/), which load data into LangChain formats from your local filesystem.
- [Web loaders](/oss/integrations/document_loaders/web_loaders/), which load data from remote sources.

See the individual pages for more on each category.

<Info>
If you'd like to write your own document loader, see [this how-to](/oss/how-to/document_loader_custom/). If you'd like to contribute an integration, see [Contributing integrations](/oss/contributing#add-a-new-integration).
</Info>
